1. Field of the Invention
The field relates to an optical information recording medium on which optically reproducible information is recorded or can be recorded, and more particularly, to an optical information recording medium having an image forming layer on which an image can be formed with aqueous ink with a recording layer therebetween on the surface of a substrate opposite to an incident surface on which recording light and reproduction light are incident, in which display performance with aqueous ink on the image forming layer.
2. Description of the Related Technology
In these days, CDs (Compact Discs) are spread in the field of audio and CD-ROMs are widely used as optical media for storing data with spread of PCs (Personal Computers). Further, with development and practical use of short-wave laser, DVDs (Digital Versatile Discs) allowing recording and reproduction of data with a higher density are widely used and with development and practical use of shorter-wave laser such as blue laser, optical disks corresponding to a HD DVD standard or a Blu-ray standard allowing recording and reproduction of data with a higher density are spread. As the DVDs, there is known a DVD-ROM for computer data, in addition to a digital video disk for video image. In the near future, a DVD dedicated to music is going to come to the market.
The CD or CD-ROM has a structure that a light transmitting substrate, which is a donut-shaped disk made of resin such as polycarbonate, is coated with gold or aluminum to form a reflection layer and is covered with a protection layer made of UV-curable resin or the like. In order to record data thereon, uneven pit lines are formed in a spiral arrangement on the surface of the light transmitting substrate. The pit lines are formed in advance at the time of forming the light transmitting substrate along a mold such as a stamp and the reflection layer is formed thereon.
The DVD or DVD-ROM has the same basic structure as the CD or CD-ROM. The thickness of the light transmitting substrate is a half of that of the CD and thus by bonding two sheets of light transmitting substrates having the half thickness, the total thickness of the disk is equal to that of the CD. For example, in a one-sided DVD or DVD-ROM, uneven pit lines are formed on one substrate, the reflection layer is formed thereon, and then another substrate not having the pit lines and the reflection layer is bonded thereto.
In addition to the CDs or DVDs on which data are recorded in advance by the use of the pit lines, optical information recording mediums such as CD-R, CD-RW, DVD-R, and DVD-RW on which data can be recorded after optical information recording mediums are manufactured are developed and used.
As such an optical information recording medium, there is developed an optical information recording medium on which an image can be printed with aqueous ink by the use of an aqueous ink pen or an inkjet printer, by forming an ink receiving layer for receiving aqueous ink on various layers such as a recording layer on the surface of the light transmitting substrate opposite to the surface on which recording light or reproduction light is incident. In the optical information recording medium, the ink receiving layer for fixing the aqueous ink on the surface of a protection layer or the surface of the bonded substrate.
Such a related art is disclosed in Japanese Unexamined Patent Application Publication No. 2004-216614.
Color print with high image quality is performed much by the use of inkjet printers. The color print is performed by jetting a plurality of color droplets to pixels of the ink receiving layer from an ink nozzle and adjusting colors and concentrations through the combination of colors or the amount of jetted inks. In this case, in order to obtain natural and good coloring, it is required that a plurality of ink colors jetted to the pixels are rapidly absorbed and fixed to the ink receiving layer without being mixed. In addition, in order to improve a water-resistant property such that solid attachment or thinning on the printed image could be prevented or the printed image could not be damaged due to moisture in air or moisture of a hand handling the optical information recording medium, it is necessary that the ink jetted onto the surface of the ink receiving layer is absorbed into and fixed to the ink receiving layer.
In order to accomplish rapid absorption and fixation of the aqueous ink into the ink receiving layer, the hydrophilic property of the ink receiving layer should be enhanced. However, in this case, it is also easy for the ink receiving layer to absorb the moisture of a hand or the moisture in air, so the solid attachment can easily occur. Accordingly, for example, when the optical information recording mediums are stacked for storage, the upper and lower ones are bonded to each other, thereby damaging the display quality and making the handling thereof difficult. The printed portion with the ink is blurred by the absorption of the moisture and the ink holding property is deteriorated, thereby reducing the durability of the print quality.
For these reasons, it is difficult to embody high image quality such as image quality of a photograph by allowing the opposite requirements of enhancement in ink absorption property of the ink receiving layer and the prevention of the solid attachment to be compatible with each other.